The present invention relates to devices configured for implanting beneath a patient's skin and more particularly to such devices incorporating a battery for powering electronic circuitry for various purposes including tissue, e.g., nerve or muscle, stimulation and/or parameter monitoring and/or data communication.
Implantable devices for tissue stimulation (i.e., microstimulators) are known in the art. See, e.g., U.S. Pat. Nos. 5,193,539; 5,193,540; 5,312,439; 5,324,316; 5,358,514; 5,405,367; 5,571,148, which are incorporated herein by reference.
Such known microstimulators are characterized by a sealed housing which contains electronic circuitry for producing small electric currents between spaced electrodes. By precisely implanting the microstimulators proximate to targeted tissue, the currents will stimulate the nerve to produce medically beneficial results.
Typically, such prior microstimulators derive operating power from an internal coil that is inductively coupled to an external AC magnetic field produced, for example, by a drive coil mounted proximate to the microstimulator. An AC voltage induced in the internal coil is rectified and filtered to produce a DC operating voltage which is used to power the electronic circuitry. Such an arrangement requires that the user remain in close proximity to the drive coil to maintain tissue stimulation.